Layer forming method and apparatus

ABSTRACT

There is provided a method and apparatus to deposit a molybdenum comprising layer on a substrate by supplying a precursor comprising molybdenum(VI) dichloride dioxide and a first reactant comprising boron and hydrogen to the substrate in a reaction chamber to react and form the molybdenum layer. The first reactant comprising boron and hydrogen may be diborane.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of U.S. Provisional Patent Application Ser. No. 62/836,344, filed Apr. 19, 2019 and entitled LAYER FORMING METHOD AND APPARATUS, the disclosure of which is hereby incorporated by reference.

FIELD

The present disclosure generally relates to a method and apparatus to form a layer on a substrate. More particularly, the disclosure relates to a method and an apparatus for depositing a molybdenum comprising layer on a substrate in a reaction chamber.

The deposition method may comprise supplying a precursor comprising molybdenum dichloride dioxide and a first reactant to the substrate in the reaction chamber to let a portion of the precursor and the first reactant react to form the molybdenum layer. The layer on the substrate may be used for manufacturing of a semiconductor device.

BACKGROUND

In atomic layer deposition (ALD) and chemical vapor deposition (CVD), a substrate is subjected to a precursor and a first reactant suitable for reacting into a desired layer on the substrate. The layer may be deposited in a gap created during manufacturing of a feature on the substrate to fill the gap.

In ALD, the substrate is exposed to a pulse of the precursor and a monolayer of the precursor may be chemisorbed on the surface of the substrate. The surface sites may be occupied by the whole of or by a fragment of the precursor. The reaction may be chemically self-limiting because the precursor may not adsorb or react with the portion of the precursor that has already been adsorbed on the substrate surface. The excess of the precursor is then purged, for example by providing an inert gas and/or removed with a pump from a reaction chamber. Subsequently, the substrate is exposed to a pulse of the first reactant, which chemically reacts with the adsorbed whole or fragment of the precursor until the reaction is complete and the surface is covered with a monolayer of the reaction product.

It has been found that there may be a need to improve the quality of the deposition process for molybdenum layers.

SUMMARY

This summary is provided to introduce a selection of concepts in a simplified form. These concepts are described in further detail in the detailed description of example embodiments of the disclosure below. This summary is not intended to identify key features or essential features of the claimed subject matter, nor is it intended to be used to limit the scope of the claimed subject matter.

There may be a need for an improved method to form a deposited molybdenum layer on a substrate. Accordingly, in an embodiment, there may be provided a method of depositing a molybdenum comprising layer on a substrate in a reaction chamber. The method may comprise supplying a precursor comprising molybdenum(VI) dichloride dioxide (MoO₂Cl₂) to the substrate in the reaction chamber. The method may comprise supplying a first reactant to the substrate in the reaction chamber to let a portion of the precursor and the first reactant react to form the molybdenum layer. The first reactant may comprise boron and hydrogen.

By having the first reactant comprising boron and hydrogen, the reactivity of the first reactant with the precursor comprising molybdenum(VI) dichloride dioxide (MoO₂Cl₂) may be improved. Deposition of the molybdenum layer may therefore be improved. The quality of the total layer may be improved and/or the speed of the deposition process may be improved.

In some other embodiments, a method for semiconductor processing is provided. The method includes depositing a metal layer into a gap in the substrate, thereby filling the gap.

According to a further embodiment there is provided a deposition apparatus to deposit a molybdenum comprising layer on a substrate comprising:

a reaction chamber provided with a substrate holder to hold a substrate;

a heating system constructed and arranged to control the temperature of the substrate;

a distribution system comprising valves to provide in the reaction chamber a precursor and at least a first reactant; and,

a sequence controller operably connected to the valves and being programmed to enable deposition of molybdenum on the substrate in the reaction chamber with the precursor and the first reactant, wherein the distribution system is provided with a precursor delivery device to deliver a molybdenum(VI) dichloride dioxide (MoO₂Cl₂) vapor and a first reactant delivery system constructed and arranged to deliver a vapor of a first reactant comprising boron and hydrogen.

BRIEF DESCRIPTION OF THE DRAWINGS

While the specification concludes with claims particularly pointing out and distinctly claiming what are regarded as embodiments of the invention, the advantages of embodiments of the disclosure may be more readily ascertained from the description of certain examples of the embodiments of the disclosure when read in conjunction with the accompanying drawings, in which:

FIGS. 1a and 1b show a flowchart illustrating a method of depositing a layer according to an embodiment.

DETAILED DESCRIPTION

Although certain embodiments and examples are disclosed below, it will be understood by those in the art that the invention extends beyond the specifically disclosed embodiments and/or uses of the invention and obvious modifications and equivalents thereof. Thus, it is intended that the scope of the invention disclosed should not be limited by the particular disclosed embodiments described below.

The illustrations presented herein are not meant to be actual views of any particular material, structure, or device, but are merely idealized representations that are used to describe embodiments of the disclosure.

As used herein, the term “substrate” may refer to any underlying material or materials that may be used, or upon which, a device, a circuit, or a film may be formed.

As used herein, the term “cyclic deposition” may refer to the sequential introduction of one or more precursors (reactants) into a reaction chamber to deposit a film over a substrate and includes deposition techniques such as atomic layer deposition and cyclical chemical vapor deposition.

As used herein, the term “cyclical chemical vapor deposition” may refer to any process wherein a substrate is sequentially exposed to one or more volatile precursors, which react and/or decompose on a substrate to produce a desired deposition.

As used herein, the term “atomic layer deposition” (ALD) may refer to a vapor deposition process in which deposition cycles, preferably a plurality of consecutive deposition cycles, are conducted in a reaction chamber. Typically, during each cycle, the precursor is chemisorbed to a deposition surface (e.g., a substrate surface or a previously deposited underlying surface such as material from a previous ALD cycle), forming a monolayer or sub-monolayer that does not readily react with additional precursor (i.e., a self-limiting reaction). Thereafter, if necessary, a reactant (e.g., another precursor or reaction gas) may subsequently be introduced into the process chamber for use in converting the chemisorbed precursor to the desired material on the deposition surface. Typically, this reactant is capable of further reaction with the precursor. Further, purging steps may also be utilized during each cycle to remove excess precursor from the process chamber and/or remove excess reactant and/or reaction byproducts from the process chamber after conversion of the chemisorbed precursor. Further, the term “atomic layer deposition,” as used herein, is also meant to include processes designated by related terms such as, “chemical vapor atomic layer deposition,” “atomic layer epitaxy” (ALE), molecular beam epitaxy (MBE), gas source MBE, or organometallic MBE, and chemical beam epitaxy when performed with alternating pulses of precursor composition(s), reactive gas, and purge (e.g., inert carrier) gas.

As used herein, the term “layer” may refer to any continuous or non-continuous structures and material formed by the methods disclosed herein. For example, “layer” could include 2D materials, nanolaminates, nanorods, nanotubes, or nanoparticles, or even partial or full molecular layers, or partial or full atomic layers or clusters of atoms and/or molecules. “Layer” may comprise material or a layer with pinholes, but still be at least partially continuous.

A molybdenum layer may be desired as a conducting layer in a semiconductor device. A method of depositing a molybdenum comprising layer on a substrate in a reaction chamber may therefore be used. The method may comprise supplying a precursor comprising molybdenum(VI) dichloride dioxide (MoO₂Cl₂) to the substrate in the reaction chamber. The precursor may comprise a molybdenum oxyhalide, not being a molybdenum oxytetrachloride (MoOCl₄). The precursor may comprise a molybdenum oxychloride, not being a molybdenum oxytetrachloride (MoOCl₄). The precursor may have Mo—O and Mo—Cl bonds, not being a molybdenum oxytetrachloride (MoOCl₄). The precursor may comprise an molybdenum oxyhalide having the same number of oxygen as chloride atoms bonded to the molybdenum. The precursor may comprise an molybdenum oxyhalide having two oxygen and two chloride atoms bonded to the molybdenum.

The method may further comprise supplying a first reactant comprising boron and hydrogen to the substrate in the reaction chamber to let a portion of the precursor and the first reactant react to form the molybdenum layer on the substrate The first reactant comprising boron and hydrogen may be selected from the group-consisting of boranes of formula B_(n)H_((n+x)), wherein n is an integer from 1 to 10 and x is an even integer.

The first reactant comprising boron and hydrogen may for example be selected from the group consisting of nido-boranes of formula B_(n)H_((n+4)).

The first reactant comprising boron and hydrogen may for example be selected from the group consisting of arachno-boranes of the formula B_(n)H_((n+6)).

The first reactant comprising boron and hydrogen may for example be selected from the group consisting of hypho-boranes of the formula B_(n)H_((n+8)).

The first reactant comprising boron and hydrogen may for example be selected from the group consisting of conjuncto-boranes BnHm. In the above examples n is an integer from 1 to 10 and m is an integer from 1 to 10 that is different from n.

The first reactant comprising boron and hydrogen may be diborane (B₂H₆). Diborane may have a structure with four terminal and two bridging hydrogen atoms. The bonds between boron and the terminal hydrogen atoms are conventional covalent bonds. The bonding between the boron atoms and the bridging hydrogen atoms may be different because two electrons have been used in bonding to the terminal hydrogen atoms each boron atom has one valence electron remaining for additional bonding. The bridging hydrogen atoms provide one electron each so the boron atoms in the diborane may be held together by four electrons. The lengths of the B—H bridge bonds may be longer than the B—H terminal bonds. This difference in the lengths of these bonds may reflect the difference in their strengths. The B—H bridge bonds of the diborane may be relatively weaker.

Reducing molybdenum dichloride dioxide (MoO₂Cl₂) with diborane (B₂H₆) may have the following reaction path MoO₂Cl₂+½ B₂H₆->Mo (s)+BOCl+HCl+H₂O. Breaking the B—H bridge bonds of the diborane may be necessary to cut the diborane in half for the reaction. Compared to the reaction path of MoO₂Cl₂+3H₂->Mo (s)+2HCl+2H₂O less molecules which may also have less strong hydrogen bonds may be involved favoring the reaction of MoO₂Cl₂ with B₂H₆. Reducing molybdenum oxytetrachloride (MoOCl₄) with diborane (B₂H₆) follows MoOCl₄+½ B₂H₆->Mo (s)+BOCl+3HCl which may lead to a higher concentration of the etchant HCl in the reaction chamber which may cause unwanted etching and/or lower the deposition rate.

Diborane may be a highly reactive and versatile reactant. Diborane has been used in the semiconductor industry, for example as a doping agent. Diborane may therefore easily be adopted in the industry as a reactant for molybdenum(VI) dichloride dioxide (MoO₂Cl₂) for the deposition of molybdenum.

The surface on which molybdenum may be deposited may comprise one sort of deposited material. Alternatively, the surface may comprise different sorts of deposited material. The surface may for example comprise aluminum oxide and/or titanium nitride. When for example a molybdenum conductive layer may be desired, it may be difficult to deposit the molybdenum on the different materials. The first layer often called seed or nucleation layer may be more difficult to deposit. It may therefore be preferred to provided molybdenum(VI) dichloride dioxide (MoO₂Cl₂) to the substrate in the reaction chamber; and, supply a first reactant comprising boron and hydrogen to the substrate in the reaction chamber to let a portion of the precursor and the first reactant react to form the molybdenum seed layer on the substrate.

Gaps created during manufacturing of a feature of an integrated circuit device may be filled with metal layers for example made with molybdenum. The gaps may have a high aspect ratio in that their depth is much larger than their width. The gaps may be extending vertically in already manufactured layers having a substantially horizontal top surface. Gaps in a vertical direction and filled with a metal may for example be used in a word line of a memory integrated circuit of the dynamic random access memory (DRAM) type. Gaps in a vertical direction and filled with a metal may for example also be used in a logic integrated circuit. For example metal filled gaps may be used as a gate fill in a P-type metal oxide semiconductor (PMOS) or complementary metal oxide semiconductor (CMOS) integrated circuit or in a source/drain trench contact.

The gaps may also be arranged in a horizontal direction in already manufactured layers. Again, the gaps may have a high aspect ratio in that their depth, now in the horizontal direction, is much larger than their width. Gaps in the horizontal direction and filled with a metal may for example be used in a word line of a memory integrated circuit of the 3D NAND type. The gaps may also be arranged in a combination of vertical and horizontal directions.

The surface of the gaps may comprise one sort of deposited material. Alternatively, the surface of the gaps may comprise different sorts of deposited material. The surface of the gaps may for example comprise aluminum oxide and/or titanium nitride. When for example a molybdenum conductive layer may be desired in the gaps, it may be difficult to deposit the molybdenum on the different material in the gaps. It may be desired that the molybdenum layers may be covering the full surface of the gaps and fill the complete gap. Further, it may be desired that the molybdenum layers may be covering the full surface of the gaps including the different sorts of material.

To fill the complete gap, a molybdenum seed layer may be deposited in the gap and a molybdenum bulk layer may be deposited on the molybdenum seed layer. The seed layer may be formed by sequentially repeating a pretreatment atomic layer deposition (ALD) cycle. It may therefore be preferred to provided molybdenum(VI) dichloride dioxide (MoO₂Cl₂) to the substrate in the reaction chamber; and, supply a first reactant comprising boron and hydrogen to the substrate in the reaction chamber to let a portion of the precursor and the first reactant react to form the molybdenum seed layer in the gap on the substrate.

Alternatively, the seed layer may be formed by a chemical vapor deposition (CVD) process. The CVD process may be pulsed wherein the first precursor is supplied with pulses onto the substrate while continuously supplying the first reactant to the substrate.

The bulk layer may be deposited on the seed layer by sequentially repeating a bulk ALD cycle. The bulk molybdenum layer may be provided on top of the molybdenum seed layer by supplying the precursor comprising molybdenum(VI) dichloride dioxide (MoO₂Cl₂) and a second reactant comprising hydrogen to the substrate in the reaction chamber, wherein a portion of the precursor and the second reactant react to form the bulk molybdenum layer. The second reactant may comprise hydrogen (H₂). The second reactant may not comprise boron. Hydrogen may be a relatively cheap and common reactant.

Alternatively, the bulk molybdenum layer may be deposited on the molybdenum seed layer by a CVD process. The CVD process may be pulsed wherein the second precursor is supplied with pulses onto the substrate while continuously supplying the second reactant to the substrate.

FIGS. 1a and 1b show a flowchart illustrating a method of depositing a molybdenum layer according to an embodiment.

The molybdenum layer may be deposited as a seed layer. The molybdenum layer may be deposited in a gap. A molybdenum bulk layer may be deposited on the seed layer.

A first ALD cycle 1 for the molybdenum seed layer may be shown in FIG. 1a . A second ALD cycle 2 for the molybdenum bulk layer may be shown in FIG. 1 b.

A substrate with a gap may be provided in step 3 in a reaction chamber. A first precursor comprising molybdenum(VI) dichloride dioxide (MoO₂Cl₂) may be supplied to the substrate in step 5 for a first supply period T1 (see FIG. 1a ). Subsequently, additional supply of the first precursor to the substrate may be stopped, for example by purging a portion of the first precursor from the reaction chamber for a first removal period R1 in step 7.

Further, the first cycle may comprise supplying 9 a first reactant to the substrate for a second supply period T2. The first reactant may comprise boron and hydrogen. The first reactant may comprise boron and hydrogen atoms in one molecule, for example it may be diborane (B₂H₆). Hydrogen gas may be added to the gas flow of the first reactant. A portion of the first precursor and first reactant may react to form at least a portion of the molybdenum seed layer on the substrate. It may take a few (around 50) cycles before deposition of the seed layer starts. Additional supply of the first reactant to the substrate may be stopped, for example by purging a portion of the first reactant from the reaction chamber for a second removal period R1 in step 10.

Optionally the first reactant may be used to clean the substrate before the seed layer is deposited. A diborane reactant may be very reactive and efficient in cleaning the surface of the substrate.

The first precursor and the first reactant may be selected to have a proper nucleation on the surface of the gaps. The first ALD cycle 1 may be repeated N times to deposit the molybdenum seed layer with N selected between 100 and 1000, preferably 200 and 800, and more preferably 300 and 600. The seed layer may have a thickness between 1 and 20, preferably 2 and 10, more preferably between 3 and 7 nm.

After the first ALD cycle 1 is repeated N times the first precursor comprising molybdenum(VI) dichloride dioxide (MoO₂Cl₂) may be supplied to the substrate in step 11 for a third supply period T3 in the bulk ALD cycle 2 (see FIG. 1b ). This may be done in the same reaction chamber as the first ALD cycle 1 of FIG. 1a or in a different reaction chamber.

It may be advantageous to do the bulk ALD cycle in a different reaction chamber than the first ALD cycle when the temperature requirement for the first cycle may be different. A substrate transfer may therefore be necessary.

Subsequently, additional supply of the first precursor to the substrate may be stopped and removed from the reaction chamber. This may be done by purging a portion of the first precursor from the reaction chamber for a third removal period R3 in step 13 towards the exhaust pump of the reaction chamber.

Further, the cycle may comprise supplying 15 a second reactant to the substrate for a fourth supply period T4. A portion of the first precursor and the second reactant may react to form at least a portion of the bulk molybdenum layer on the substrate. Additional supply of the second reactant to the substrate may be stopped for example by purging a portion of the second reactant from the reaction chamber for a fourth removal period R4 in step 17.

The first precursor and the second reactant may be selected to have proper electronical properties. For example to have a low electric resistivity. The molybdenum film may have an electrical resistivity of less than 3000 μΩ-cm, or less than 1000 μΩ-cm, or less than 500 μΩ-cm, or less than 200 μΩ-cm, or less than 100 μΩ-cm, or less than 50 μΩ-cm, or less than 25 μΩ-cm, or less than 15 μΩ-cm or even less than 10 μΩ-cm.

The second ALD cycle 2 for the bulk layer may repeated M times with M selected between 200 and 2000, preferably 400 and 1200, and more preferably 600 and 1000. The bulk molybdenum layer may have a thickness between 1 and 100, preferably 5 and 50, more preferably between 10 and 30 nm.

The process temperature may be between 300 and 800, preferably 400 and 700, and more preferably 500 and 650° C. during the first ALD cycle for the seed molybdenum layer. The vessel in which the first precursor is vaporized may be maintained between 20 and 150, preferably 30 and 120, and more preferably 40 and 110° C.

The process temperature may be between 300 and 800, preferably 400 and 700, and more preferably 500 and 650° C. during the second ALD cycle for the bulk molybdenum layer. The vessel in which the first precursor is vaporized may be maintained between 20 and 150, preferably 30 and 120, and more preferably 40 and 110° C.

Supplying the first precursor into the reaction chamber may take a duration T1, T3 selected between 0.1 and 10, preferably 0.5 and 5, and more preferably 0.8 and 2 seconds. For example, T1 may be 1 second and T3 may be 1.3 seconds. The flow of the first or second precursor into the reaction chamber may be selected between 50 and 1000, preferably 100 and 500, and more preferably 200 and 400 sccm. The pressure in the reaction chamber may be selected between 0.1 and 100, preferably 1 and 50, and more preferably 4 and 20 Torr.

Supplying the first and/or second reactant into the reaction chamber for a duration T2, T4 may take between 0.5 and 50, preferably 1 and 10, and more preferably 2 and 8 seconds. The flow of the first or second reactant into the reaction chamber may be between 50 and 50000, preferably 100 and 20000, and more preferably 500 and 10000 sccm.

Silane may also considered for the second reactant. The general formula for silane is SixH_(2(x+2)) were x is an integer 1, 2, 3, 4 . . . Silane (SiH₄), disilane (Si₂H₆) or trisilane (Si₃H₈) may be suitable examples for the second reactant having hydrogen atoms.

Purging a portion of at least one of the first precursor, the first reactant, the and the second reactant from the reaction chamber for a duration R1, R2, R3 or R4 may be selected between 0.5 and 50, preferably 1 and 10, and more preferably 2 and 8 seconds.

Purging may be used after supplying the first precursor to the substrate; after supplying the first reactant to the substrate; and after supplying the second reactant to the reaction chamber to remove a portion of at least one of the first precursor, the first reactant, and the second reactant from the reaction chamber for a duration R1, R2, R3 or R4. Purging may be accomplished by pumping and/or by providing a purge gas. The purge gas may be an inert gas such as nitrogen.

The method may be used in a single or batch wafer ALD apparatus.

The method may comprise providing the substrate in a reaction chamber and the first ALD cycles in the reaction chamber may comprise: supplying the first precursor to the substrate in the reaction chamber; purging a portion of the first precursor from the reaction chamber; supplying the first reactant to the substrate in the reaction chamber; and purging a portion of the first reactant from the reaction chamber.

Further the method may comprise providing the substrate in a reaction chamber and the bulk ALD cycles in the reaction chamber may comprise: supplying the second precursor to the substrate in the reaction chamber; purging a portion of the second precursor from the reaction chamber; supplying the second reactant to the substrate in the reaction chamber; and purging a portion of the second reactant from the reaction chamber.

Exemplary single wafer reactors, designed specifically to perform ALD processes, are commercially available from ASM International NV (Almere, The Netherlands) under the tradenames Pulsar®, Emerald®, Dragon®, Synergis® and Eagle®. The method may also be performed in a batch wafer reactor, e.g., a vertical furnace. For example, the deposition processes may be performed in an A400™, or A412™ vertical furnace available from ASM International N.V. as well. The furnace may have a process chamber that can accommodate a load of more than 100 semiconductor substrates, or wafers, having a diameter of 200 or 300 mm.

The wafer reactors may be provided with a controller and a memory which may control the reactor. The memory may be programmed with a program to supply the precursor and the reactants in the reaction chamber in accordance with the embodiments of this disclosure when executed on the controller.

The gaps that may be filled with molybdenum using the method of this disclosure may have a high aspect ratio in that the depth vertically and or horizontally is much larger than the width. For example, the aspect ratios (gap depth/gap width) of the gap may be more than about 2, more than about 5, more than about 10, more than about 20, more than about 50, more than about 75 or in some instances even more than about 100 or more than about 150 or more than about 200. The aspect ratio may be less than 1000.

It may be noted that the aspect ratio may be difficult to determine for the gap, but in this context the aspect ratio may be replaced by the surface enhancement ratio which may be the ratio of the total surface area of the gap in the wafer or part of the wafer in relation to the planar surface area of wafer or part of the wafer. The surface enhancement ratio (surface gaps/surface wafer) of the gap may be more than about 2, more than about 5, more than about 10, more than about 20, more than about 50, more than about 75 or in some instances even more than about 100 or more than about 150 or more than about 200. The surface enhancement ratio may be less than 1000.

The surface of the gaps may comprise different sorts of deposited material. The surface may for example comprise Al₂O₃ or TiN.

A conformal molybdenum metal layer may be deposited on the surface of the gap by depositing a seed layer by sequentially repeating a first ALD cycle with the first precursor and the first reactant. Further a conformal molybdenum bulk layer may be deposited by sequentially repeating a second ALD cycle with the first precursor and a second reactant on the seed layer.

Details of the used method are shown in FIGS. 1 and 1 b and the related description. In some embodiments, a deposited film comprising Mo may have a step coverage greater than about 50%, greater than about 80%, greater than about 90%, greater than about 95%, greater than about 98%, greater than about 99%.

The method may be performed in an atomic layer deposition apparatus. For example, a deposition apparatus to deposit a molybdenum comprising layer on a substrate may comprise:

a reaction chamber provided with a substrate holder to hold a substrate;

a heating system constructed and arranged to control the temperature of the substrate;

a distribution system comprising valves to provide in the reaction chamber a precursor and at least a first reactant; and,

a sequence controller operably connected to the valves and being programmed to enable deposition of molybdenum on the substrate in the reaction chamber with the precursor and the first reactant.

The distribution system may be provided with a precursor delivery device constructed and arranged to deliver a molybdenum(VI) dichloride dioxide (MoO₂Cl₂) vapor and a first reactant delivery system constructed and arranged to deliver a vapor of a first reactant comprising boron and hydrogen, for example diborane.

The first reactant may be diborane and may be supplied in the reaction chamber for a duration T2, T4 of 5 seconds with a flow of 50 and 50000 for example 495 sccm. A purge gas of nitrogen may be used after supplying the first precursor; after supplying the first precursor and after supplying the first reactant for a duration R1, R2, R3 or R4 of 5 seconds.

The process temperature may for example be around 550° C. and the pressure may be around 10 Torr during the pretreatment and bulk ALD cycles. The vessel in which the first precursor may be vaporized may be around 70° C.

The method may also be used in a spatial atomic layer deposition apparatus. In spatial ALD, the precursor and reactant are supplied continuously in different physical sections and the substrate is moving between the sections. There may be provided at least two sections where, in the presence of a substrate, a half-reaction can take place. If the substrate is present in such a half-reaction section a monolayer may form from the first or second precursor. Then, the substrate is moved to the second half-reaction zone, where the ALD cycle is completed with the first or second reactant to form one ALD monolayer. Alternatively the substrate position could be fixed and the gas supplies could be moved, or some combination of the two. To obtain thicker films, this sequence may be repeated.

Accordingly to an embodiment in a spatial ALD apparatus the method comprises:

placing the substrate in a reaction chamber comprising a plurality of sections, each section separated from adjacent sections by a gas curtain;

supplying the first precursor, e.g., molybdenum(VI) dichloride dioxide to the substrate in a first section of the reaction chamber;

(e.g., laterally) moving the substrate surface with respect to the reaction chamber through a gas curtain to a second section of the reaction chamber;

supplying the first reactant comprising boron and hydrogen, e.g., diborane to the substrate in the second section of the reaction chamber to form the molybdenum seed layer;

(e.g., laterally) moving the substrate surface with respect to the reaction chamber through a gas curtain; and

repeating supplying the first precursor and the reactant including, (e.g., lateral) movement of the substrate surface with respect to the reaction chamber to form the molybdenum seed layer.

To form the bulk layer the method may further comprise:

placing the substrate in a reaction chamber comprising a plurality of sections, each section separated from adjacent sections by a gas curtain;

supplying the first precursor, e.g., molybdenum(VI) dichloride dioxide to the substrate in a first section of the reaction chamber;

(e.g., laterally) moving the substrate surface with respect to the reaction chamber through a gas curtain to a second section of the reaction chamber;

supplying the second reactant, e.g., hydrogen (H₂) to the substrate in the second section of the reaction chamber to form the molybdenum bulk layer;

(e.g., laterally) moving the substrate surface with respect to the reaction chamber through a gas curtain; and, repeating supplying the first precursor and the second reactant including (e.g., lateral) movement of the substrate surface with respect to the reaction chamber to form the molybdenum bulk layer.

The first reactant may be comprising hydrogen and boron, for example diborane. The second reactant may be hydrogen (H₂).

In additional embodiments, the seed or bulk molybdenum layer may comprise less than about 40 at. %, less than about 30 at. %, less than about 20 at. %, less than about 10 at. %, less than about 5 at. %, or even less than about 2 at. % oxygen. In further embodiments, the seed or bulk layer may comprise less than about 30 at. %, less than about 20 at. %, less than about 10 at. %, or less than about 5 at. %, or less than about 2 at. %, or even less than about 1 at. % of hydrogen.

In some embodiments, the seed or bulk molybdenum layer may comprise halide or chloride less than about 10 at. %, or less than about 5 at. %, less than about 1 at. %, or even less than about 0.5 at. %. In yet further embodiments, the seed or bulk molybdenum layer may comprise less than about 10 at. %, or less than about 5 at. %, or less than about 2 at. %, or less than about 1 at. %, or even less than about 0.5 at. % carbon. In the embodiments outlined herein, the atomic percentage (at. %) concentration of an element may be determined utilizing Rutherford backscattering (RBS).

In some embodiments of the disclosure, forming a semiconductor device structure, such as semiconductor device structure, may comprise forming a gate electrode structure comprising a molybdenum film, the gate electrode structure having an effective work function greater than approximately 4.9 eV, or greater than approximately 5.0 eV, or greater than approximately 5.1 eV, or greater than approximately 5.2 eV, or greater than approximately 5.3 eV, or even greater than approximately 5.4 eV. In some embodiments, the effective work function values give above may be demonstrated for an electrode structure comprising a molybdenum layer with a thickness of less than approximately 100 Angstroms, or less than approximately 50 Angstroms, or less than approximately 40 Angstroms, or even less than approximately 30 Angstroms.

It will be appreciated by those skilled in the art that various omissions, additions and modifications can be made to the processes and structures described above without departing from the scope of the invention. It is contemplated that various combinations or sub-combinations of the specific features and aspects of the embodiments may be made and still fall within the scope of the description. Various features and aspects of the disclosed embodiments can be combined with, or substituted for, one another in order. All such modifications and changes are intended to fall within the scope of the invention, as defined by the appended claims. 

What is claimed is:
 1. A method of depositing a molybdenum comprising layer on a substrate in a reaction chamber, the method comprising: supplying a precursor comprising molybdenum (VI) dichloride dioxide (MoO₂Cl₂) to the substrate in the reaction chamber; and, supplying a first reactant to the substrate in the reaction chamber to let a portion of the precursor and the first reactant react to form the molybdenum layer, wherein the first reactant comprises boron and hydrogen.
 2. The method according to claim 1 wherein the molybdenum layer is a seed layer.
 3. The method according to claim 2, wherein the method further comprises providing a bulk molybdenum layer to the seed layer by a method comprising: supplying the precursor comprising molybdenum (VI) dichloride dioxide (MoO₂Cl₂) to the substrate in the reaction chamber; and, supplying a second reactant comprising hydrogen to the substrate in the reaction chamber, wherein a portion of the precursor and the reactant react to form the bulk molybdenum layer.
 4. The method according to claim 3, wherein the second reactant comprises hydrogen (H₂).
 5. The method according to claim 1, wherein the precursor is supplied with pulses into the reaction chamber and the pulses are between 0.1 and 10 seconds.
 6. The method according to claim 1, wherein the flow of the precursor into the reaction chamber is between 50 and 1000 sccm.
 7. The method according to claim 1, wherein the flow of the first reactant into the reaction chamber is between 50 and 50000 sccm.
 8. The method according to claim 1, wherein the pressure in the reaction chamber is between 0.1 and 100 Torr.
 9. The method according to claim 1, wherein the process temperature is between 300 and 800° C.
 10. The method according to claim 1, wherein depositing the molybdenum layer comprises repeating an atomic layer deposition (ALD) cycle comprising sequentially supplying the precursor and the first reactant to the substrate.
 11. The method according to claim 10, wherein in between supplying the first precursor and the first reactant the substrate is purged between 0.5 and 50 seconds.
 12. The method according to claim 11, wherein supplying the first reactant into the reaction chamber takes between 0.5 and 50 seconds.
 13. The method according to claim 1, wherein the first reactant comprising boron and hydrogen is selected from the group-consisting of boranes of formula B_(n)H_((n+x)), wherein n is an integer from 1 to 10 and x is an even integer.
 14. The method according to claim 13, wherein the first reactant comprising boron and hydrogen is selected from the group consisting of nido-boranes of formula B_(n)H_((n+4)).
 15. The method according to claim 13, wherein the first reactant comprising boron and hydrogen is selected from the group consisting of arachno-boranes of the formula B_(n)H_((n+6)).
 16. The method according to claim 13, wherein the first reactant comprising boron and hydrogen is selected from the group consisting of hypho-boranes of the formula B_(n)H_((n+8)).
 17. The method of claim 13, wherein the first reactant comprising boron and hydrogen is diborane (B₂H₆).
 18. The method according to claim 1, wherein the first reactant comprising boron and hydrogen is selected from the group consisting and conjuncto-boranes BnHm, wherein n is an integer from 1 to 10 and m is an integer from 1 to 10 that is different from n.
 19. The method according to claim 1, wherein before the precursor is provided to the reaction chamber the first reactant comprising boron and hydrogen is provided in the reaction chamber to prepare the surface of the substrate.
 20. The method according to claim 1, wherein the substrate comprises one or more gaps created during manufacturing of a feature on the substrate and the one or more gaps are at least partially filled by the method of depositing a molybdenum comprising layer on a substrate in a reaction chamber.
 21. A deposition apparatus to deposit a molybdenum comprising layer on a substrate comprising: a reaction chamber provided with a substrate holder to hold a substrate; a heating system constructed and arranged to control the temperature of the substrate; a distribution system comprising valves to provide in the reaction chamber a precursor and at least a first reactant; and, a sequence controller operably connected to the valves and being programmed to enable deposition of molybdenum on the substrate in the reaction chamber with the precursor and the first reactant, wherein the distribution system is provided with a precursor delivery device to deliver a molybdenum(VI) dichloride dioxide (MoO₂Cl₂) vapor and a first reactant delivery system constructed and arranged to deliver a vapor of a first reactant comprising boron and hydrogen. 